#![allow(dead_code)] use std::panic::UnwindSafe; use std::cell::RefCell; fn assert<T: UnwindSafe + ?Sized>() {} fn main() { assert::<&RefCell<i32>>(); //~^ ERROR the type `UnsafeCell<i32>` may contain interior mutability and a //~| ERROR the type `UnsafeCell<isize>` may contain interior mutability and a }